BRITISH WARBLERS 



and in fact appears to be a favourite material. If the branches 

 of the honeysuckle are examined, it will be noticed that the 

 bark of itself peels off and splits up into long soft strands. 

 The female consequently has little difficulty in tearing off the 

 smaller shreds, with which she forms the foundation of the 

 nest ; and so much does it resemble decayed grasses that it is 

 often a difficult matter to distinguish it. Honeysuckle abounds 

 in many places resorted to by the Willow Warbler, and its 

 bark is easily collected. It formed the foundation of all three 

 nests constructed by the first female in No. 2 territory, and 

 also of those in the adjoining territories. In fact it is con- 

 stantly used both by this species and the Chiff-chaff. What 

 particular merit can there be in its use ? Why should it be 

 preferred to dead grass? The use of it cannot be of "selection" 

 value, for bark is not obtained more easily than decayed grass ; 

 the weaving of it into the foundation of the nest cannot make 

 for stability, and an individual that persistently ignored the 

 use of it would be in no worse a position, since other material 

 in abundance is always close at hand. No doubt an earlier 

 generation would have regarded the habit as an intelligent 

 modification transmitted from parent to offspring, but such a 

 view cannot now be entertained, and the behaviour of the birds 

 does not admit of an appeal to tradition. It is just one of 

 those details which so readily escape our attention on account 

 of their triviality. We ask ourselves how comes it that this 

 material should be used by different individuals and so fre- 

 quently, call to our aid known laws and theories which in 

 other directions successfully explain certain facts, apply them 

 one by one, and finally lay them aside as unsound or insuffi- 

 cient, humiliated by the vastness of that which we deemed 

 unimportant. The interior part of the nest is formed of the 

 decayed stems of finer grass, intermingled with moss and dead 

 leaves, the lining being usually feathers, but the third nest of 

 the first female in No. 2 territory contained no feathers. All 

 the nests that have come under my notice were situated on the 

 ground, and, where possible, a sloping bank seems to be pre- 



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